The present invention relates generally to application-specific integrated circuit (ASIC) design. More specifically, but without limitation thereto, the present invention relates to methods and systems for testing Input/Output (IO) cells used in application-specific integrated circuit (ASIC) design.
A variety of IO cells are used in ASIC's. The functionality of these cells is increasing as the process geometries of these cells is decreasing. When these cells are used in ASIC, it would be desirable to test these IO cells on an ASIC tester. In order to test these IO cells on an ASIC tester, though, oftentimes additional logic is needed (i.e., surrounding the IO cells). The number of cells (in variety) which require extra logic to test them is increasing. Also, the logic required to test IO cells is different for different types of IO cells.
Basically, at the present time, there is no standard way or automated way to test IO cells in an ASIC design, and when IO cells are tested, it is done manually. Manually testing IO cells is generally difficult, time consuming and prone to errors. Oftentimes, designers are under time pressures to meet deadlines. As a result of there being no standard way or automated way to test IO cells, the fact that manual testing is so difficult, time consuming and prone to errors, and the fact that ASIC designers are often under time pressure, designers often skip (either entirely or partially) the step of testing the IO cells, and the IO cells go untested or perhaps only partially tested. As a result, parts in the ASIC may fail. Even if the IO cells are tested, they are typically tested manually. As a result, different testing variations may be attempted, and this usually makes it difficult to debug a problem in case of failure.
LSI Logic, the Assignee of the present invention, provides a design system called “FlexStream” (which is a registered trademark of LSI Logic (all rights reserved)). As shown in FIG. 1, the FlexStream® design system is configured such that an ASIC designer uses certain third party tools (i.e., implementation, verification and manufacturing test tools) to design an ASIC, and uses LSI Logic's FlexStream® design system to analyze the design. The FlexStream® design system is a fully integrated environment for complex ASIC and System-on-a-Chip (SoC) design. It provides a complete system-to-silicon methodology that enables first-pass silicon success to meet tight time-to-market windows. The FlexStream® design system is an integration of best-in-class LSI Logic and third party EDA tools. This approach provides an ASIC designer with the flexibility to use their preferred tools. The ASIC designer designs with efficiency and confidence because LSI Logic's strong partnerships with EDA vendors assure that third party tools are well-integrated into the FlexStream® environment. In addition to design capabilities, the FlexStream® design system provides a link between all the design components—process technology, libraries and memories, CoreWare functions, advanced packaging solutions, and manufacturing, test, and assembly. While the FlexStream® design system which is currently available provides many advantages, it does not define a system or provide the necessary guidelines or information needed to effectively test the IO cells of an ASIC.